This invention relates to an apparatus for changing the charge distribution in a blast furnace, and more particularly to an apparatus which changes the blast furnace charge distribution by moving a large number of plates disposed in a circle in the top portion of the blast furnace top for changing the inclination thereof with respect to the central vertical axis of the furnace.
A conventional apparatus for changing the blast furnace charge distribution, known as a tilting type apparatus, comprises a large number of arms each carrying a plate of a tough material, such as armor plate, fixed to the lower portion thereof and disposed in a circle within the top of the blast furnace, the upper end of each arm being hinged to the furnace shell so that the arm is pivotable with respect to the shell. The furnace charge, comprising iron ore, coke and so on, from a large bell, falls against the plates and is deflected thereby and then drops into the furnace. The position to which the charge falls in the furnace can be adjusted by changing the position and inclination of the plates.
FIGS. 1 and 2 show an example of such a conventional blast furnace charge distribution apparatus. A large number of arms 9 are pivotally suspended in a circle in the top of a furnace shell, each arm being pivotably mounted on the shell by a metal hanger 8 at a point above a gas uptake 2. A plate 10 is fixed to the lower portion of each arm 9. A driving ring 11 encircles the shell 1 at substantially the same level as the plates 10 and is movably mounted for movement around the shell. The driving ring 11 drives a plurality of crank levers 12, one for each arm 9. One end of each crank lever 12 is connected to the driving ring for being rotated thereby, and the other end thereof is pivotally connected to the rear end of a horizontal push rod 13 passing through the furnace shell. The foremost end of the horizontal push rod is connected to the lower part of the corresponding arm 9. The driving ring 11 also has connected thereto a hydraulic piston-cylinder mechanism 14 which moves the ring 11 around the shell. When the hydraulic cylinder 14 moves the driving ring 11 around the furnace shell 1, all the crank levers 12 rotate about their vertical axes at the same time. As a consequence, the horizontal push rods 13, connected to the crank levers 12, move back and forth to change the position and inclination of the plates 10. When the plates 10 are placed in an appropriate position, the charge falls along the bell 4 and along trajectory 5, striking plates 10 and then falling along trajectory 6 to the desired position 7 in the furnace.
The conventional apparatus of this type has the arms 9 suspended from a very high part of the furnace shell 1, so that the plates 10 are inclined only slightly even when pushed inward as far as they will go and, therefore, and unable to deflect the charge to the center of the furnace. Further, because the plates are exposed to a rapid stream of gas, the plates 10 wear down quickly. The great length of the arms 9 and the large size of the plates 10 make their replacement difficult. The vertical and horizontal movement of the horizontal push rod 13 during operation prevents perfect gas sealing, which leads to a heavy inflow of dust into the casing 15 of the push rod drive means. In addition, the presence of the driving ring 11, crank levers 12, hydraulic cylinder 14, etc. outside the furnace shell 1 presents considerable danger to the operators.
Other examples of a tilting type charge distribution changing apparatus are found in Belgium Pat. No. 672,912 and German Pat. No. 625,591. They are also unable to change the position and inclination of the plates to any great extent, so that the control over the furnace charge distribution is also limited in these apparatuses.
FIG. 3 shows another example of a conventional apparatus. A base 17 is attached to the foremost end of a horizontal push rod 16, and an inclined plate 18 is fastened to the base 17 at an appropriate angle. The base 17 is supported on rollers 20 which roll on a bracket 19. The rear end of the horizontal push rod 16 is connected to driving means (not shown) that causes the horizontal push rod 16 to move back and forth. This apparatus controls the charge distribution in the furnace by changing the position of the plates 18. Since the inclination of the plates 18 is fixed, this type of apparatus cannot change or adjust the charge distribution over a very wide area of the furnace.
British Pat. No. 1,177,333 discloses yet another type of charge distribution changing apparatus. This apparatus changes the furnace charge distribution by means of a large number of vertical plate segments which are supported by link mechanisms for horizontal and radial movement within the furnace. Because only the position, and not the inclination, of the segments is adjustable, this apparatus also is incapable of controlling the furnace charge distribution over a wide area. Moreover, the plate segment drive mechanism, each comprising the combination of a link mechanism and a bell crank, are complex.